Peripersonal Space-Time, A neural system capturing body-environment relationships in space and time

Animals perceive the external world and act on it from a specific location of space, centered around their physical body, and at a given moment in time. The neural bases of space representation have been extensively studied. A key representation for action, perception, and consciousness is the Peripersonal Space (PPS), defined as the space surrounding the body (“peri-” + “persona”). PPS is a neural representation, i.e., a network of neurons distributed mainly in fronto-parietal circuits, integrating multisensory stimuli from the body with external stimuli occurring close to the body, as a function of their distance. Traditionally, the defining feature of PPS has been its spatial aspect, i.e., distance from the body. However, the PPS system is heavily dependent on temporal features, as it is sensitive to dynamic stimuli (changing position over time) and can for instance predict potential interactions in the near future based on sensory information available in the present and near past. The current project thus proposes that PPS is a neural mechanism that captures not only spatial but also temporal contingencies between the body and external stimuli, creating a spatiotemporal map of potential interactions between the individual and the environment.

The project will explore how temporal dynamics influence PPS multisensory integration mechanisms. By simultaneously manipulating spatial and temporal relationships between bodily (e.g., touch, proprioception) and external (e.g., visual, auditory) stimuli, we aim to uncover that the Peripersonal Space-Time (PPST) system entails a unified spatiotemporal representation. We will describe how such representation is constructed based on statistical regularities of bodyenvironment interactions. Combined psychophysics and electrophysiology (EEG) experiments will investigate how tactile information on the body is integrated with external stimuli across spatial (distance), temporal (delay), and combined dimensions, thereby mapping the spatiotemporal field of multisensory integration that defines PPST under normal conditions. Results will provide the empirical description of the spatiotemporal PPST field and a validated methodology to measure it.

This project has the potential to make significant contributions to our understanding of how the brain builds a multisensory representation of the body in space and time, building our everyday experience of living “here and now”. This will greatly advance our understanding of two key related fields of space and time representation. Functionally, it will expand our knowledge of how the brain integrates spatial and temporal information to anticipate and react to environmental events. Translationally, this knowledge can be applied to study psychiatric disorders related to the self and to altered multisensory processing, such as schizophrenia and autistic spectrum disorders.